Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in an uplink (UL) transmission. Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3GPP) long term evolution (LTE) and LTE-Advanced (LTE-A).
In 3GPP radio access network (RAN) LTE and LTE-A systems, the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). Examples of a UE include a mobile terminal, a tablet computer, a personal digital assistant (PDA) and a machine-type communication (MTC) device. The downlink (DL) transmission can be a communication from the node (or eNodeB) to the wireless device (or UE), and the uplink (UL) transmission can be a communication from the wireless device to the node. Instead of communication via eNodeBs, communication between wireless equipment can be performed using peer-to-peer or device-to-device communication.
D2D communications utilizing the LTE/LTE-A spectrum and/or high frequency band spectrum, for example, frequency band above 6 GHz, not currently used by LTE/LTE/A offer the possibility of extending the maximum transmission distance for direct communication between wireless devices (possibly up to around 1000 m) relative to technologies such as Bluetooth (10-100 m approximate range) and Wi-Fi direct (200 m approximate range) and can reduce the costs and scalability problems potentially associated with the backhaul connection required for picocell/femtocell/relay infrastructure-based networks. D2D communications according to the present technique may also comprise Peer-to-Peer (P2P) communications involving direct communication between network entities or wireless equipment at the same hierarchical level of the wireless network, for example direct communications between picocells, femtocells and relays as well as direct communications between wireless devices such as UEs. Wireless equipment includes at least a UE, a picocell, a femtocell and a relay node.
LTE/LTE-A provides both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes of communication. There is a requirement as 4G LTE/LTE-A wireless communication systems evolve towards 5G to support a system bandwidth wider than the 100 MHz bandwidth limit of current LTE-A and to provide latency that is reduced relative to the current LTE/LTE-A minimum user plane latency of around 5 milliseconds (ms) and a Hybrid Automatic Repeat Request (HARQ) round trip time (RTT) of around 8 milliseconds. Automatic Repeat reQuest (ARQ) is a retransmission protocol where the receiver checks for errors in the received data and upon detection of an error, discards the data and requests retransmission from the sender. Hybrid ARQ (HARQ) is a retransmission protocol in which, if an error in received data is detected, the receiver buffers the data and requests retransmission from the sender. An HARQ receiver improves performance of the retransmissions by combining the re-transmitted data with the buffered data prior to channel decoding and error detection. There is also a requirement to support reduced latency reliably whilst accommodating dynamically varying traffic demands for transmission and/or reception.